The present invention relates to systems and methods for analyzing samples, in particular cell samples and, more particularly, to a cell sorting system which enables accurate and rapid sorting of individual cells based on magnetic properties of cell specific tags as well as other characterizing properties and in addition enables efficient cell manipulation (e.g. genetic engineering) followed by optional cryo preservation at A single cell level.
Numerous approaches for screening samples for the presence of specific cell types or analytes are known in the art. For example, fluorescence activated cell sorting (FACS) is a technique often used to identify and isolate cells of interest based on the presence of a cell specific optical marker. Magnetic activated cell sorting (MACS) is also known in the literature and is based on the presence of a cell specific magnetic marker.
Isolation of specific cell types from cell samples (e.g. biological samples or cell cultures) is important in both diagnostic and therapeutic medicine.
For example, identification of specific cell types in a cell sample derived from a subject can indicate the presence of a pathology (e.g. cancer) or predisposition to such a pathology while isolation of adult stem cells (e.g. mesenchymal stem cells—MSCs) can be used in subsequent cell therapy.
The latter use is of particular importance since strategies for regenerating tissue are being developed in response to a range of clinical needs, including replacement of damaged or genetically absent metabolic functions and repair or restructuring of damaged tissues.
Due to limitations associated with isolation and use of embryonic stem cells, MSCs and hematopoietic stem cells (HSCs) are increasingly gaining favor as potential sources for cell therapy. Such cells can be used to generate neural, skeletal as well as hematopoietic progenitors and as such can be used in a variety of cell based therapies.
Isolation of specific cell types is typically effected through unique cellular markers or characterizing traits. Separation procedures, such as FACS, typically utilize tags (e.g. fluorescent antibodies) that specifically bind the cell of interest. Such tags can be directed at cell surface markers (e.g., CD4 and CD8 on lymphocytes) or at cytoplasmic or nuclear markers (specific gene sequence).
The key steps in the process of separation is the ability to identify and label a particular marker/characteristic of interest on a cell using a cell specific tag and use a property of the tag to manipulate the cell. Numerous types of tags exist in the art including fluorescently labeled antibodies, antibodies linked to a member of a binding pair (e.g. avidin-biotin), receptor-specific ligands labeled with fluorescent dyes and the like. For a review of commonly used cell tags, please see, Introduction to Flow Cytometry, Cambridge University Press, James V. Watson, Apr. 26, 1991).
One approach for cell manipulation involves use of tags, which include magnetic, conductive or paramagnetic particles. Such tags can be manipulated by a magnetic field and thus cells attached thereto can be isolated using the magnetic property of the tag. A review of magnetic cell tagging approaches is provided by Chalmers et al in “Flow Through, Immunomagnetic Cell Separation Biotechnol” (Prog. 1998, 14, 141-148; and DePalma in “Developments in Biomagnetic Separations Focus on New Affinity Mechanisms” (Genet. Eng. News 1997, 17, 11).
Although systems capable of magnetic separation of tagged cells are known in the art such systems are incapable of typing non-tagged cells and thus are limited to bulk sorting and isolation of desired cells only. In addition, prior art systems are also limited by a lack of cell manipulation and preservation capabilities, and thus cells sorted by such systems must be further processed to enable preservation, a severe limitation especially in cases were the cells of interest must be manipulated as part of the process and stored under cell preserving conditions.
Thus, it would be highly advantageous to have a system devoid of the above mentioned limitations, which system would be capable of sorting, isolating, manipulating and preserving tagged or non-tagged cells rapidly and easily.